Answer: all of the above
Explanation: if you pay with cash, or a debit card you won't have to rack up any debt and pay interest on it -- interest that will only add to the cost of your trip.
A credit card prevents your bank account from being accessed in case of fraud.
No matter what you do, all the options could work best for you in the end.
i believe your options choices was
- pay cash for their vacation
- put the vacation on their credit card but pay the bill in full each month
- use a debit card for their vacation
- all of the above